Intraocular, accommodating lens and methods of use

ABSTRACT

An intraocular lens comprises an optical element adapted to be implanted within the capsular bag of a human eye. The optical element includes one or more internal layers formed by one or more planes that are moveable relative to one another in order to effect the power of the optical element.

REFERENCE TO PRIORITY DOCUMENT

This application is a continuation of co-pending U.S. application Ser.No. 12/343,406, filed Dec. 23, 2008, which claims priority of U.S.Provisional Patent Application Ser. No. 61/018,837 filed Jan. 3, 2008.The disclosures of the aforementioned applications are herebyincorporated by reference in their entirety.

BACKGROUND

The present disclosure relates generally to the field of ophthalmics,more particularly to ophthalmic devices, including intraocular lenses(IOLs) such as accommodating intraocular lenses.

A healthy young human eye can focus an object in far or near distance,as required. The capability of the eye to change back and forth fromnear vision to far vision is called accommodation (see for example, Burdet al. “Mechanics of accommodation of the human eye” Vision Research39:1591-1595 (1999); Chien et al. “Analysis of human crystalline lensaccommodation” J. Biomech. 39:672-680 (2006)). Accommodation occurs whenthe ciliary muscle contracts to thereby release the resting zonulartension on the equatorial region of the capsular bag of the eye. Therelease of zonular tension allows the inherent elasticity of the lenscapsule to alter to a more globular or spherical shape, with increasedsurface curvatures of both the anterior and posterior lenticularsurfaces.

When the ciliary muscle is relaxed, the ciliary muscle moves into thedisaccommodated configuration, which is posterior and radially outwardfrom the accommodated configuration. The radial outward movement of theciliary muscles creates zonular tension on the lens capsule to stretchthe equatorial region of lens toward the sclera. The disaccommodationmechanism flattens the lens and reduces the lens curvature (bothanterior and posterior). Such natural accommodative capability thusinvolves altering the shape of the lens to the appropriate refractiveparameters for focusing the light rays entering the eye on the retina toprovide both near vision and distant vision.

Intraocular lens implantation for cataracts is the most commonlyperformed surgical procedure in elderly patients in the U.S. Nearlythree million cataract surgeries are performed each year in the U.S.,with an additional 2.5 million surgeries in Europe and Asia. Inconventional extracapsular cataract surgery, the crystalline lens matrixis removed leaving intact the thin walls of the anterior and posteriorcapsules—together with zonular ligament connections to the ciliary bodyand ciliary muscles. The crystalline lens core is removed byphacoemulsification through a curvilinear capsularhexis and replacedwith an intraocular lens. Unfortunately, conventional IOL's, even thosethat profess to be accommodative, may be unable to provide sufficientaxial lens spatial displacement along the optical axis or lens shapechange to provide an adequate amount of accommodation for near vision.

Several attempts have been made to make intraocular lenses that providethe ability to accommodate. However, there is still a need for anaccommodative intraocular lens that can adequately change shape tosimulate the action of a natural lens.

SUMMARY

It would be advantageous to provide IOLs adapted for accommodatingmovement which can achieve an acceptable amount of accommodation.

In one aspect, there is disclosed an intraocular lens, comprising anoptical element adapted to be implanted within the capsular bag of ahuman eye. The optical element includes one or more internal layersformed by one or more planes that are moveable relative to one anotherin order to effect the power of the optical element. In an embodiment, afemtosecond laser having a wavelength in the range of about 1100 nm toabout 1200 nm is used to form the internal planes.

In another aspect, there is disclosed a method of forming an intraocularlens, comprising providing an optical body that is adapted to beimplanted within the capsular bag of a human eye; and releasing energyat a location internal to the optical body to create one or moreinternal layers separated by planes, wherein the inner layers aremoveable relative to one another in order to effect the power of theoptical element.

In another aspect, there is disclosed an intraocular lens, comprising anoptical element adapted to be implanted within the capsular bag of ahuman eye. The optical element includes one or more chambers that arefilled with a material that changes shape in response to forces actingupon the material.

These general and specific aspects may be implemented using the devices,methods, and systems or any combination of the devices, methods andsystems disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a human eye.

FIG. 2 shows an IOL that is adapted to be implanted within the capsularbag of a human eye.

FIG. 3 shows a lateral, cross-sectional view of an IOL having internalplanes.

FIG. 4 shows a posterior, cross-sectional view of the IOL of FIG. 3.

FIG. 5 shows a lateral, cross-sectional view of another embodiment of anIOL having internal planes.

FIG. 6 shows a posterior, cross-sectional view of the IOL of FIG. 5.

FIG. 7 shows a lateral, cross-sectional view of another embodiment of anIOL having internal planes.

FIG. 8 shows a posterior, cross-sectional view of the IOL of FIG. 7.

FIG. 9 shows a lateral, cross-sectional view of another embodiment of anIOL having internal planes.

FIG. 10 shows a posterior, cross-sectional view of the IOL of FIG. 9.

FIG. 11 shows a schematic representation of internal planes being formedin an IOL.

FIG. 12 shows a perspective view of another IOL that is adapted to beimplanted within the capsular bag of a human eye.

FIG. 13 shows a cross-sectional view of the IOL of FIG. 12.

FIG. 14 shows a lateral view of the IOL in FIG. 12 in the accommodatedstate.

FIG. 15A shows a lateral view of the IOL in FIG. 12 in a disaccommodatedstate.

FIG. 15B shows a representative displacement of the IOL in FIG. 12during disaccommodation.

FIG. 16 shows a cross-sectional view of another embodiment of an IOL.

FIG. 17 shows a cross-sectional view of the IOL of FIG. 16 in thedisaccommodated state.

FIGS. 18 and 19 show another embodiment of an IOL.

FIG. 20 shows a layered IOL model.

FIG. 21 shows the tabulated results for a solid, unlayered IOL andModels 1 through 5.

FIGS. 22-26 show various IOL modeling characteristics.

FIG. 27 shows a graph of the IOL force versus radial displacement forModels 2 and 5.

FIG. 28 shows a graph of the IOL force versus power change.

FIGS. 29-30 are graphs showing comparing the IOL efficiency of Models 2and 5.

DETAILED DESCRIPTION

Before the present subject matter is further described, it is to beunderstood that this subject matter described herein is not limited toparticular embodiments described, as such may of course vary. It is alsoto be understood that the terminology used here in is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting. Unless defined otherwise, all technical terms used herein havethe same meaning as commonly understood by one skilled in the art towhich this subject matter belongs.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope of the subject matterdescribed herein. Any recited method can be carried out in the order ofevents recited or in any other order which is logically possible.

Definitions

The terms zonular region or zonular contact region refer to the portionof the capsular bag that is typically contacted by or attached to thezonules. One way to describe the zonular contact region is as theportion of the capsular bag which is contacted by the zonules and whichcorresponds to that defined by the equatorial apices of the capsular bagand an orthogonal projection upon the capsular bag radius from theportion of the capsular bag contacted by the zonules. The determinationof a capsular bag radius dimension in its accommodative orunaccommodative states can be made in various manners. For example, thedetermination of capsular bag radius dimension in its accommodative orunaccommodative states can be made using the Scheimpflug slit imagetechnique (Dubbelman, Vision Research, 2001; 41:1867-1877), and IR videophotography (Wilson, Trans. Am. Ophth. Soc. 1997; 95:261-266). Theaforementioned references are incorporated herein by reference.Generally the zonular contact region is about 1.5-2.0 mm radially inwardfrom the equatorial apices along the capsular bag radius.

The term percentage (X%) of zonular contact refers to the contact orattachment area along the capsular bag defined by the equatorial apicesof the capsular bag and an orthogonal from a given percentage (%) of thecapsular bag radius defining the zonular contact region. For example,contacting 50% of the zonular contact region refers to contacting thatportion of the capsular bag that corresponds to the portion defined bythe equatorial apices and a radii of 50% of the zonular contact regionradii. For the purposes of example, if the zonular contact region has aradii of 1.5 mm, then the respective 50% would be that region defined bythe equatorial apices and a contact region defined in part by theorthogonal at 0.75 mm or an orthogonal projection from 0.75 mm radiallyinward from the equatorial apices.

The term anterior portion of the zonular region refers to the mostanterior portion of capsular bag contacted by the zonular region.

The term posterior portion of the zonular region refers to the mostposterior portion of the capsular bag contacted by the zonular region.

The term shape changing optical element refers to an optical elementthat is made of material that enables the optical element to alter itsshape, e.g. become one of more spherical in shape, thicker or focus on acloser object; or become more ovoid in shape, thinner or focus on a moredistant object and thus alter the optical element's respective optics(alter the diopters of the resulting optical element).

The term accommodating shape refers to the shape of the optical elementwhen at least one of the tensioning of the ciliary muscle of themammalian eye, the zonules of the mammalian eye and a change in thevitreous pressure in the eye effect equatorial or polar distention ofthe capsular bag to effect a focusing upon a closer object. Anaccommodating shape is generally more spherical than thedisaccommodating shape.

The term disaccommodating shape refers to the shape of the opticalelement when at least one of the relaxation of the ciliary muscle of themammalian eye, the zonules of the mammalian eye and a change in thevitreous pressure in the eye and a comcomittant change to a more ovoidshaping of the capsular bag to effect a focusing upon a more distantobject. A disaccommodating shape is generally more ovoid than theaccommodating shape.

Capsulorhexis is the opening surgically made by puncturing, thengrasping and tearing a hole in the anterior capsule. In a regularextracapsular cataract extraction (ECCE) procedure, a capsulorhexis ismade in the anterior capsule and the cloudy cataract lens is extractedby phacoemulsification. The accommodative IOL described herein can beused for patients after cataract surgery. It can also be used forpatients with only presbyopia, but without cataract.

The term diopter (D) refers to the reciprocal of the focal length of alens in meters. For example, a 10 D lens brings parallel rays of lightto a focus at (1/10) meter. After a patient's natural crystalline lenshas been surgically removed, surgeons usually follow a formula, based ontheir own personal preference, to calculate a desirable diopter power(D) for the selection of an IOL for the patient to correct the patient'spreoperational refractive error. For example, a myopia patient with −10D undergoes cataract surgery and IOL implantation; the patient can seeat a distance well enough even without glasses. This is because thesurgeon has taken the patient's −10 D near-sightedness into account whenchoosing an IOL for the patient.

The term medially disposed within the capsular sac refers to beingdisposed within the generally equatorial region of the capsular bag,e.g., between the anterior and posterior portions of the capsular bag.

Exemplary Embodiments of Intraocular Lens

An accommodative intraocular lens (IOL) is adapted for surgicalreplacement of the natural crystalline lens in the human eye. FIG. 1shows cross-sectional view of the human eye 100 prior to implantation ofan IOL. The eye 100 includes an anterior portion 105 and a posteriorportion 110. A cornea 115 is located on the anterior portion 105. Thecornea 115 encloses and forms an anterior chamber 120, which containsaqueous fluid and is anteriorly bounded by an iris 125. A capsular bag130 contains the natural crystalline lens 135. The capsular bag 130includes an anterior wall 140 a and a posterior wall 140 b. The eye 10further includes a ciliary muscle 145 attached to the capsular bag 130via zonules 150. The vitreous humor is located posterior to the capsularbag 130 and anterior to the retina (not shown). The vitreous humorcontains vitreous fluid.

The ciliary body 145 accomplishes ocular adjustments for focusing ofobjects viewed at different distances. In this regard, the ciliary body145 acts on the capsular bag 130 and the natural crystalline lens 135through the zonules 150. The ciliary body 145 contracts to allow thecapsular bag 130 to return to a more spherical shape for viewing objectsnear to the viewer. When the ciliary body 145 retracts, the ciliary body145 pulls on the zonules 150 to “flatten” the capsular bag 130 to permitobjects at a distance to be viewed in proper focus: Thus, when the eyefocuses, the capsular bag 140 changes shape to appropriately distributethe light admitted through the cornea 115 and the iris 125.

FIG. 2 shows an IOL 205 formed of an optical body that is adapted to beimplanted within the capsular bag 130 of a human eye 10. When positionedin the capsular bag 130, the IOL 205 changes shape in response tomovement of the ciliary body 145 for focusing of objects viewed atdifferent distances. In this regard, the IOL 205 includes one or morelayers that are formed by internal surfaces or planes 210 (representedby a dashed line in FIG. 2) that are moveable relative to one another inorder to affect the power of the IOL. When the planes move relative toone another, the focusing characteristics of the IOL 205 are changed topermit the lens to focus on objects at different distances. The IOL 205in FIG. 2 has only a single internal plane 210 (or a pair of internalsurfaces that are juxtaposed). However, it should be appreciated thatthe IOL 205 can include various quantities of internal planes of variousshapes, sizes, and positions, as described in more detail below.

Each of the layers formed by the internal planes 210 comprises at leastone surface formed internally within the IOL. The surfaces arejuxtaposed with one another such that the surfaces can slide relative toone another. The presence of the layers formed by the internal planesmakes the IOL 205 more susceptible to changes in shape than if theinternal layers were not present. In an embodiment, at least some of thesurfaces are in direct contact with one another and slidable relative toone another. In another embodiment, at least some of the surfaces areseparated by a solid or liquid medium, such as hydrogel or silicone oil.Each of the surfaces can act as an individual lens body that refractslight. The lens material and the intervening medium each can have arefractive index that can be identical or generally identical such thatreflection of light at the interface of the materials is minimized oreliminated. For example, an IOL can have lens material of siliconerubber having surfaces separated by a liquid medium of silicone oil.Silicone rubber and silicone oil have essentially the same refractiveindex thereby resulting in minimal light reflective effects of thejuxtaposed surfaces. Similarly, any light reflective effects due toaberrations in the lens material and the creation of edges due to lasercuts within the lens would be minimized. The materials and methods usedin the manufacture of the disclosed IOLs are discussed in more detailbelow.

The internal layers formed by the planes can have a property such thatthe IOL is inclined to change shape such as in a predetermined manner.The property that enables the shape change can vary and can include, forexample, the structure, position, shape, size, pattern, Young's modulus,thickness, etc. The property can be relative to another layer or it canbe absolute property. For example, the internal layers can bepositioned, shaped, sized and/or patterned to maximize the amount ofshape change in one or more locations of the IOL, such as within thecenter of the IOL. In an embodiment, at least one internal layer ispositioned within a volume defined by 3 mm radius from the geometriccenter of the IOL.

FIG. 3 shows a lateral, cross-sectional view of an IOL 205 havinginternal layers formed by planes 210 that are arranged as a series ofconcentric, circular-shaped surfaces. When viewed from the side, theinternal planes 210 are arranged in a side-by-side pattern with theplanes 210 having a gradually reduced dimension D moving outwardly fromthe center of the IOL. As mentioned, the internal planes 210 definesurfaces internal to the IOL wherein the surface on either side of eachplane 210 can move relative to one another, as represented by the arrowsX1 and X2 for plane 210 a. The internal planes 210 can have any of avariety of contours including flat or curviplanar contours orcombinations thereof. FIG. 4 shows a posterior, cross-sectional view ofthe IOL of FIG. 3. The internal planes 210 when viewed from theposterior viewpoint are concentrically-arranged circles.

As shown in FIG. 4, the outer perimeter edges of each layer formed by aplane 210 can be entirely contained within the internal volume of theIOL such that the outer surface of the IOL is uninterrupted by thepresence of the internal plane. Alternately, at least a portion of theouter edge of an internal plane can extend to the outer surface of theIOL such that the plane forms a cleavage on the outer surface of theIOL.

With reference again to FIG. 3, the layers formed by internal planes 210are shown as being generally parallel to one another. However, it shouldbe appreciated that the internal planes 210 can be arranged innon-parallel relationships.

FIG. 5 shows a lateral, cross-sectional view of an IOL 205 having layersformed by internal planes 210 that are arranged as a series ofconcentric spherical or partial spherical surfaces within the internalvolume of the IOL. In other words, the internal planes 210 are arrangedin an “onion skin” fashion of gradually reducing spheres. It should beappreciated that the internal planes in the embodiment of FIG. 5 are notnecessarily spherical but can be any type of concentrically-arrangedthree-dimensional shapes. As mentioned, the planes 210 form juxtaposedsurfaces that are adapted to move relative to one another as exhibitedby the arrows X1 and X2 in FIG. 5. The movement can be three-dimensionalin that the surfaces can slide relative to one another along a planedefined by the planes themselves. In an embodiment, the surfaces canalso move toward and away from one another. FIG. 6 shows a posterior,cross-sectional view of the IOL of FIG. 5.

FIG. 7 shows a lateral, cross-sectional view of another embodiment of anIOL 205 wherein a layer formed by an internal plane 210 forms at leastone internal core member 605 within the IOL. The core member 605 can bedefined by the internal plane 210 such that the surface of core member605 can be movable relative to the remainder of the IOL 205. As shown inthe posterior, cross-sectional view of FIG. 8, the core member 605 canbe circular in cross-section from a posterior viewpoint, although theshape of the core member can vary. FIGS. 9 and 10 show lateral andposterior cross-sectional views, respectively, of an IOL having internalplanes that form multiple core members 605. The internal planes 210 canbe used to form any number of core members 605 of various shapes withinthe IOL 205.

The layers formed by internal plane(s) 210 can be formed within theinterior of the IOL 205 in various manners. In an embodiment, lensessuch as those manufactured by Biovision (WIOL™ C/CF; WIOL™ USI;Biovision s.r.o.; Prague, Czech Republic) can be modified using anynumber or orientation of cuts in the lens to form internal planes thatachieve movement during accommodation (Pasta et al.,“Pseudoaccommodation of WIOL CF Hydrogel lenses” ASCRS 2006 SanFrancisco, Calif. PowerPoint presentation;http://www.biovision.cz/wiol-cf.pdf; Biovision Web Presentation). In anembodiment, an energy source can be used to form the interior planes. Anapplicator can be coupled to the energy source and energy focused withinan interior region of the IOL 205. A level of energy released at adesired location or series of locations within the IOL can be sufficientto cleave a plane interior to the IOL and thereby form the internalplanes 210. The release of energy can be guided along a contour orpathway such that energy is released to cleave a plane of a desiredshape within the IOL.

This process is represented schematically in FIG. 11, wherein anapplicator 1105 releases a stream of energy 1110 into the IOL. Thestream of energy can be focused at an internal location 1115 such that asufficient level of energy is released at the location 1115. The IOL canbe thereby cleaved at the location 1115 to form at least a portion ofthe internal plane.

In an embodiment, the energy source can be a laser used to form theinternal plane 210 that forms the layer. Any type of laser that can befocused very precisely to achieve cleavage over a small volume of theIOL can be used. The laser can be configured to form an internalcleavage in the IOL without affecting the outer surface of the IOL. Inan embodiment, a femtosecond laser having a wavelength in the range ofabout 1100 nm to about 1200 nm is used to form the internal plane. In anembodiment, the lens can undergo a power change of approximately 0.5diopters to approximately 5 diopters.

Additional Embodiments

In another embodiment, the lens is adapted to change from a first shapeto a second shape during implantation into the lens capsule or after thelens has been implanted in the lens capsule. The shape change can occurautomatically, such as in response to a change in temperature, or it canoccur upon manual activation by a clinician. For example, the lens maybe manufactured of a material that is adapted to undergo a shape changein response to a predetermined stimulus.

In one embodiment, the lens can be manufactured in the accommodatedstate and implanted into the lens capsule. During or after implantationinto the lens capsule, the lens undergoes a shape change to conform tothe shape of the capsule. Some exemplary materials are hydrogel, acrylicand silicone. In the case of the lens being manufactured of hydrogel,the lens can be hydrated after implantation into the lens capsule tocause the lens to change shape, such as to conform to the shape of thecapsule. The lens may be bonded to the capsule so that the lens moveswith the capsule during ciliary muscle contraction and relaxation.

FIG. 12 shows a perspective view of an IOL 2605 in an accommodatedstate. FIG. 13 shows a cross-sectional view of the IOL 2605. The IOL2605 has an internal chamber that provides the IOL 2605 with a flexiblenature that permits or encourages a shape change. The chamber canoptionally be filled with a material that changes shape in response toforces acting upon the material. The material can be a liquid, a gas, ora solid, including a gel. Possible materials include, but are notlimited to, air, silicone, oil, and hydrogel. The calculation of thelens power takes into account the type of material that is used to fillthe chamber, to account for the optical interaction between the materialand the inner surface of the chamber as well as the outer surface of thelens. In this regard, the refractive indices of the material in thechamber and the material of the lens can be selected to achieve adesired lens power. For example, the lens material and the material inthe chamber can be selected to have refractive indices that areidentical or generally identical such that reflection of light at theinterface of the materials is minimized or eliminated.

FIG. 14 shows a lateral view of the IOL 2605 in the accommodated statesuch that the zonules Z are relaxed. In FIG. 15A, the zonules Z aretensioned so that the IOL 2605 is in the unaccomodated state. Note thatthe IOL 2605 has taken on a flattened shape with respect to theaccommodated state.

FIG. 15B shows a representative displacement of the IOL 2605 as thezonules tense. As mentioned, the IOL flattens as the zonules tense. TheIOL can be adapted to undergo different displacement or shape changes indifferent regions of the lens. For example, in the embodiment of FIG.15B, the IOL undergoes a relatively large displacement D in the centralanterior region.

In yet another embodiment, the IOL includes one or more chambers thatare filled with a flowable material, such as hydrogel or silicone oil.The material can flow from one chamber to one or more other chambers inresponse to stimuli. The flow of material between the chambers causesthe IOL to undergo a shape change. For example, FIG. 16 shows across-sectional view of an IOL having a central chamber 3005 and one ormore lateral chambers 3010 that are fluidly connected to the centralchamber 3005. A flowable material resides in one or more of thechambers. In FIG. 16, the IOL is in an accommodated state such that allor a majority of the flowable material resides in the central chamber3005. This causes the central chamber to have an expanded state relativeto the lateral chambers 3010.

In response to stimuli, the flowable material flows out of the centralchamber 3005 as represented by arrows F in FIG. 17. The material flowsinto the lateral chambers 3010 to expand the lateral chambers 3010. Thiscauses the IOL to flatten in shape.

FIGS. 18 and 19 show another embodiment of an IOL comprised of two ormore pieces 3205 a and 3205 b that collectively form a fresnel lensregion 3210. The pieces each have a respective refractive index that canbe the same or different from one another. When implanted in the eye,the two pieces are adapted to separate from one another, as shown inFIG. 19, or to move toward one another, as shown in FIG. 18, in responseto zonular tension or lack thereof. When separated from one another asshown in FIG. 19, a space can form between the two pieces 3205 a and3205 b wherein the material within the space has a refractive indexdifferent than the refractive index of the material from which thepieces are formed. The change in refractive index effectively forms alens between the two pieces of the IOL.

The IOL can be manufactured using a variety of materials including, butnot limited to silicone; silicone acrylate; acrylic; hydrogel (includingurethanes, acrylamides, silicones, acrylics, polysaccharides,poly(N-vinylpyrrolidones), poly(hydroxyethylmethacrylate), acrylonitrile(AN) copolymers; polyacrylonitrile (PAN) polymers; PAN homopolymers;hydrophilic co-monomers (including acrylamide, vinyl pyrrolidone,styrene sulfonic acid, vinylsulfonic acid etc.); hydrophilic polymers;hydrophobic co-monomers (including alkyl acrylates or methacrylates,styrene, vinylchloride, methylstyrene, vinylpyrridine etc.); hydrophobicpolymers; and polymethylmethacrylate (PMMA). Exemplary materials used inthe manufacture of IOLs are described in U.S. Pat. Nos. 6,232,406;6,451,922; and 6,617,390, each of which are incorporated by referenceherein.

The IOL can also be manufactured using a variety of methods andmanufacturing processes. For example, the IOLs disclosed herein can bemanufactured by shaping methods such as extrusion, casting, molding(including injection molding, compression molding, insert molding,etc.), dipping, spinning or similar shaping method. The IOLs disclosedherein can also be shaped using micromachining techniques, such as witha femtosecond laser. For example, a solid hydrogel lens can be sliced orcleaved with a laser thereby forming internal planes and a desired shapewithin the IOL. Other exemplary methods used in the manufacture andprocessing of IOLs are described in U.S. Pat. Nos. 5,674,283; 4,971,732;4,893,918 and 4,806,287, each of which are incorporated by referenceherein.

In an embodiment, the IOLs disclosed herein (205 or 2605 ) can be placedin situ by a procedure in which an incision is made in the eye. Afterthe incision is formed, the original lens can be removed from the eye.The IOL 205 or 2605 can then be positioned within the eye and theincision closed. Any suitable procedure, including procedures in whichthe original lens or a portion of the original lens is not removed, maybe used. The IOL 205 or 2605 can be used in conjunction with existingcontacts, glasses, the natural lens, another IOL or any other suitableoptical device, or the IOL 205 or 2605 can be used alone. Further, theIOL 205 or 2605 can be positioned in any suitable chamber (e.g.,anterior or posterior) or within any suitable tissue or structure. TheIOL 205 or 2605 also can be attached to the existing or natural lens inany suitable manner, or the IOL 205 or 2605 can be detached from orreplace the existing or natural lens.

EXAMPLE Mechanical Analysis of Multilayered Accommodating IOLs

Multilayer IOL designs such as IOL 205, having internal planes 210arranged as a series of concentric spherical surfaces within theinternal volume of the IOL, as shown in FIG. 3, were analyzed inisolation to characterize the optical power change-to-equatorial forcerelationship. This analysis used nonlinear axissymmetric finite elementmodeling of a three-layer prototype.

As shown in FIG. 20, the modeling assumed frictionless sliding/contactconditions and a prescribed equatorial/radical displacement of 0.3 mm.

Five models were developed, assuming different combinations of Young'smodulus for elasticity. Young's modulus (E elasticity modulus), definedas the ratio of tensile stress to tensile strain, describes tensileelasticity, or the tendency of an object to deform along an axis whenopposing forces are applied along that axis.

The following table shows the different combinations of Young's modulusused for each of the five examples of three-layered IOLs.

Table of Layered IOL Models' Elasticity Values (in MPa) Inner MiddleOuter Model 1  0.1 MPa  0.1 MPa 0.1 MPa Model 2 0.01 MPa  0.1 MPa 0.1MPa Model 3 0.01 MPa 0.01 MPa 0.1 MPa Model 4 0.01 MPa 0.01 MPa 0.01MPa  Model 5 0.003 MPa  0.003 MPa  0.03 MPa 

The curvature per power ratio is based upon an aperture of 2.5 mm indiameter and a refractive index difference of 0.1. The optical powerchange is calculated using the following formula, where DP is thediopter power change, n₂−n₁=0.1, and R is the radius in mm:

${DP} = {2*1000*\left( {n_{2} - n_{1}} \right)*\left\lbrack {\frac{1}{R_{final}({mm})} - \frac{1}{R_{init}({mm})}} \right\rbrack}$

FIG. 21 shows the tabulated results for a solid, unlayered IOL andModels 1 through 5. FIG. 22 shows the vertical displacement contours(mm) for the solid section, FIG. 23 for Model 1, FIG. 24 for Model 2,FIG. 25 for Model 3 and 5, and FIG. 26 for Model 4.

A solid, unlayered IOL is the reference point for the analysis. It isobserved that power is independent of Young's modulus; but dependent onthe Poisson ratio (bulk modulus). Since the solid, unlayered lens isincompressible (Poisson ratio ˜0.5), its performance is fixed. Thesolid, unlayered IOL gives a power change of −1.434 D and a diopter toforce ratio of 0.036 D/gram-force.

With regard to the layered IOLs, it is observed that power is controlledby the ratio of the layers' Young's moduli; not their absolute values.For example, Models 3 and 5 give the same power change; in particular,the best results come from models with a relatively stiff outer layer.

The total force required to achieve a 0.3 mm radial displacement dependson the value of the outer layer's Young's modulus; thus, it is observedthat Models 3 and 5 have different zonular force requirements.

The effect of changing the modulus ratios is nonlinear because of thesliding contact. Optimal design is achieved by controlling both layermoduli ratios and absolute values; for example, Model 5 produces −4 Dpower with less than 6 grams of zonular force.

The efficiency of the designs is given by the power per unit zonularforce; for example, Model 5 is approximately 20 times more efficientthan the solid section. In an unexpected result, Model 5 offers a powerchange that is 2.86 times larger than the unlayered, solid IOL under a0.3 mm radial displacement, while the zonular force required to achievethat displacement in Model 5 is 0.15 times that of the solid, unlayeredIOL.

FIG. 27 shows a graph of the IOL force versus radial displacement forModels 2 and 5. Model 2 requires more force for the same amount ofdisplacement than Model 5. FIG. 28 shows a graph of the IOL force versuspower change. For the same amount of radial force, Model 5 produces alot more power change. FIGS. 29-30 are graphs showing comparing the IOLefficiency of Models 2 and 5; Model 5 is considerably more efficient inproducing diopter changes than Model 2.

Based upon the foregoing analysis, IOLs that are made from the samematerial are not very effective in producing diopter changes. Theunexpected result is that, in order to increase the efficiency of theIOLs, the outer layer must be stiffer than the inner layers, as can beobserved from the results obtained for Model 5.

IOLs of the type used in Model 5 can be obtained in various ways. Forexample, a femtosecond laser can be used to morcellate the inner layers,to decrease their bulk modulus, while the Young's modulus of the outerlayer remains high.

Another alternative method of producing an IOL of the Model 5 typeinvolves using a silicone outer layer, while injecting silicone oil intoa hollow inner layer. Silicone oil has the same refractive index assilicone polymer, and thus the visual acuity through these IOLs will notbecome compromised.

Another method of producing IOLs of the Model 5 type comprises moldingan inner layer of low Young's modulus material, and then overmolding thesubsequent layers on top of the initial inner layer.

Although embodiments of various methods and devices are described hereinin detail with reference to certain versions, it should be appreciatedthat other versions, embodiments, methods of use, and combinationsthereof are also possible and within the scope of the claims. Thereforethe spirit and scope of the appended claims should not be limited to thedescription of the embodiments contained herein. Certain features thatare described in this specification in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable sub-combination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asub-combination or a variation of a sub-combination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.

Only a few examples and implementations are disclosed. Variations,modifications and enhancements to the described examples andimplementations and other implementations may be made based on what isdisclosed.

1. A method of forming an intraocular lens, comprising: providing anoptical body adapted to be implanted in a human eye, the optical bodycomprising a unitary structure formed of only a single material;releasing energy from an energy source at a location internal to theoptical body; and creating with the released energy a plurality ofsurfaces extending through a portion of the unitary structure formingone or more concentric internal layers and an outer layer, wherein theone or more concentric internal layers are surrounded by the outer layerat a first region and the one or more concentric internal layers becomethe outer layer at a second region, and wherein each of the plurality ofsurfaces forms first and second juxtaposed internal surfaces that areslideably moveable relative to one another in order to effect the powerof the optical body.
 2. A method as in claim 1, wherein the energysource is a laser.
 3. A method as in claim 2, wherein the laser formsthe one or more concentric internal layers without affecting the outersurface.
 4. A method as in claim 1, wherein the energy source is afemtosecond laser having a wavelength in the range of about 1100 nm toabout 1200 nm.
 5. A method as in claim 1, wherein the intraocular lensis adapted to undergo a power change of approximately 0.5 diopters toapproximately 5 diopters.
 6. A method as in claim 1, wherein the firstand second juxtaposed internal surfaces are in direct contact andslideable relative to each other.
 7. A method as in claim 1, furthercomprising separating the first and second juxtaposed internal surfacesby a solid, liquid, or gas medium.
 8. A method as in claim 7, whereinthe medium is hydrogel or silicone oil.
 9. A method as in claim 8,wherein the medium and the optical body have identical refractiveindices.
 10. A method as in claim 1, wherein at least one property ofthe one or more concentric internal layers is adapted to maximize anamount of shape change in one or more locations of the lens.
 11. Amethod as in claim 10, wherein the at least one property is a thicknessof one internal layer relative to another internal layer.
 12. A methodas in claim 10, wherein the at least one property is a Young's modulusof one internal layer relative to another internal layer.
 13. A methodas in claim 10, wherein that at least one property is a position of oneinternal layer relative to another internal layer.
 14. A method as inclaim 1, wherein the optical body further comprises one or more chambersfilled with a flowable material.
 15. A method as in claim 1, wherein theouter layer is stiffer than the one or more concentric internal layersat the first region.
 16. A method as in claim 1, wherein the opticalbody is adapted to be implanted within a capsular bag of a human eye.